1. Field of the Disclosure
The present disclosure is related to directional drilling and includes methods for determining a tool face angle of a drill string drilling a wellbore.
2. Description of the Related Art
In petroleum exploration and drilling, it is often desirable to drill a wellbore into a hydrocarbon reservoir at an angle rather than drilling down vertically to the reservoir. When drilling an angled wellbore, at some point it becomes necessary to change the direction of a drill string drilling the wellbore from its original vertical orientation. This practice is known as directional drilling. The rate of change of a drilling direction can be controlled by an operator or program that orients a drill bit at the end of the drill string toward a selected direction. A useful parameter for determining drilling direction is known as the tool face angle or orientation of the drill string along the azimuth of the drill string. Due to drilling dynamics, the drill string can twist and oscillate, thereby causing uncertainty in the operator's knowledge of the tool face angle and making it difficult to control the drilling direction. Therefore, the present disclosure provides a method and apparatus for estimating a tool face angle of a drill string downhole.